1. Field of the Invention
The present invention relates to a technology for managing products or the like using an individual recognition technique by radio frequency identification (RFID).
2. Description of the Related Art
Currently, an individual recognition technique by RFID is applied to various fields of manufacturing, physical distribution, apparel and the like. As an example, the case of introducing the RFID system to a production line is described below. An RFID tag is attached to a product or its component in advance. When an antenna allocated along the production line detects the RFID tag while a worker is performing a manufacturing process, the test process of a product or the like on a production line, information about the product or component, such as its work contents, a test result or the like is sequentially written into the RFID tag. By referring to the data stored in the RFID tag, the state of a component or product to which the RFID tag is managed.
FIG. 1 shows each process in the case where a conventional RFID system is introduced to a production line. A product 150 is sequentially conveyed to a work area 1, a work area 2 and so on and a prescribed process is applied to it in each work area. In the example shown in FIG. 1, in the work area 1 the history data of the product is written into the RFID tag, in the work area 2 a threshold used in a test in a test area is calculated, in the work area 3 the process management is carried out and in the work area 4 a function test is conducted. In this way, process contents which the control unit of the RFID system applies to the RFID tag in each work area are prescribed.
In the conventional RFID system, the control unit side, that is, the RFID system side has all the process functions executed for the RFID tag in each work area. The RFID tag has data necessary for processes and when the RFID system detects the RFID tag by its antenna, the control unit reads necessary data from the RFID system and performs various processes.
FIG. 2 shows the processing method of the conventional control system. Conventionally, the control unit, that is, the system side has information about the contents to be processed and their process order. Therefore, the control unit sequentially executes subroutines according to the information held by the control unit using the fact that the antenna of the system detects the RFID tag as a trigger.
FIG. 3 shows the technical problem of the conventional RFID system. In the work area 1, history data is written into the RFID tag. In the work area 2, the threshold(s) used in a test of a component or product to which the RFID tag is attached is (are) calculated. In the work area 3, process management, such as the issuance of “kanban (a just-in-time instruction)” or the like, is performed. In the test area, a function test is applied to a components or product to which the RFID tag is attached.
Firstly, the problem caused when the history data is written into the RFID tag is described. FIG. 4 shows the problem caused when the history data is inputted.
In the production line, the history to be recorded of a component or the like (a component and a product) is registered in a master database. Then, when the component is carried to the prescribed shelf of the work area and the antenna detects its existence, its version number registered in the master database (DB) is written into the RFID tag. The component or the like to which the RFID tag is attached is sequentially stored in the box placed on the shelf and is carried out to a subsequent work area when the storage into the box is completed. Another box is placed in the place where the old box was placed and the component is stored in the new box.
Conventionally, although the writing of the history data into the RFID tag is executed by the control unit of the RFID system, the master DB for managing a version number to be written is manually updated by reading using a bar code, manual input by a system manager or the like. Specifically, the master DB must be updated before another box is placed in the same place after a box filled by components is carried out of the work line and when the update timing of the master DB delays, there occurs a mismatch between the arrangement on the master DB of the component and actual arrangement and the version number of another already carried component is written into the RFID tag.
FIG. 5 shows the problem caused when a test is conducted. When conducting the test of a component or the like, since the RFID tag itself has no operation function, the RFID system calculates data used for the test, download test program, and conducts the test using data calculated.
A test, or its analysis and the like takes time, whereas a product to be tested moves on the carrier line while conducting the test and analyzing its result. Therefore, if abnormality is detected as a result of the test, the analysis of the test result in the control unit sometimes is not completed while the product is moving on the test line. If the process in the control unit cannot catch up with the moving speed of the line, sometimes a necessary operation can be performed in another system. However, in this case, the operation result from the other system must be awaited. In such a case, the carrier line must be stopped temporarily until the operation on the other system is completed.
FIG. 6 shows the problem caused in the process management. In this case, it is assumed that a prescribed work, such as the assembly or the like, of product 1 is executed firstly, and subsequently that of product 2 is executed in the work area 3 of the production line. It is also assumed that products 1 and 2 use components A and B, respectively.
According to just-in-time (JIT) system, “kanban” is issued taking into consideration a period needed from the procurement of a specific component to manufacturing and test of a product in such a way as to procure the component in a specific work area at a specific necessary time. In the example shown in FIG. 6, in order to procure component A for work area 3, kanban must be issued when component A exists in work area 2 and as to component B, kanban must be issued when component B exists in work area 1. In this way, the timing of issuing kanban depends on the type of a product (work) and differs for each type of a product (work).
Furthermore, the timing of issuing kanban differs every day depending on a work area, the type of a component and a lead time. However, conventionally since the control unit controls the timing of issuing kanban, in order to change the timing of issuing kanban every day, data stored in the control unit must be updated every day.
Although the process starts using the detection of the RFID tag in the control unit of the RFID system as a trigger, the sub routines are sequentially executed in the control unit before its result is written into the RFID tag after the process starts. Therefore, the RFID tag must wait for the completion of the writing of the result on the line. Since the RFID tag does not store process contents to be executed in each process and data used for each process and the RFID system controls them, a specific process according to a specific RFID tag cannot be performed in an appropriate timing, which is the problem.